When forming a hole in a processing target film in an etching process using plasma, it is known that a reaction product generated from the processing target film adheres to the hole, causing the hole to be clogged. As a countermeasure to the clogging of the hole, Patent Document 1 discloses a technique of adjusting an etching rate of the processing target film in the etching process by controlling a temperature of an electrostatic chuck on which a processing target object is placed.
Patent Document 1: Japanese Patent Laid-open Publication No. 2016-225437
In the aforementioned technique of adjusting the temperature of the electrostatic chuck, however, although the clogging of the hole may be suppressed to some degree, an apparatus configuration becomes complicated. That is, in the aforementioned prior art, since the temperature of the electrostatic chuck is adjusted by controlling a flow rate of a coolant flown in a coolant path formed within a base configured to support the electrostatic chuck, the apparatus configuration applied to the control of the flow rate of the coolant becomes highly complicated.
In view of this, it may be considered to use a method of removing the reaction product adhering to the hole by plasma of a processing gas instead of performing the temperature adjustment of the electrostatic chuck. In this case, Ar/O2 is generally used as the processing gas to remove the reaction product adhering to the hole, particularly, a reaction product which contains carbon. In case of removing the reaction product adhering to the hole by using plasma of the Ar/O2, however, it is difficult to remove a reaction product which contains silicon, so that roundness of the hole may be deteriorated. Therefore, it is required to improve the shape of the hole.